The trend of rising obesity rates in the past decade may be reversing among US preschoolers, according to the first national study to report a decline in the condition among young children.

The research by the US Centers for Disease Control and Prevention found that the number of obese 2- to 4-year-olds from low-income families dropped 1.8 percent from 2003 to 2010, while those who were extremely obese fell 6.8 percent. The findings were published today in a research letter in the Journal of the American Medical Association.

“We’ve flipped from going up to really now showing a decrease,” said Heidi Blanck, acting director of the Division of Nutrition, Physical Activity and Obesity at the Atlanta-based CDC. “It’s a modest decrease, but at least we’ve changed the direction.”